The Sikh writer, publisher, political commentator, conservationist and philanthropist Patwant Singh, who has died after a cardiac arrest aged 84, had a very rare ability to communicate compellingly with the wider world on many issues without losing touch with his deeply held faith.

Of his dozen books, half were written in his last 15 years. Red-hot anger runs though the political books on India, from his memoir Of Dreams and Demons (1994) to The Second Partition: Fault-Lines in India's Democracy (2007) – anger at what he saw as the death of Nehru's ideals, the "lumpenization" of Indian politics, the factional killings and sickening recurrence of religious violence, the hollowness of India's glowing world image as a rising great power when one in four of its people live on a dollar a day. Two books of these last years, the classic The Sikhs (1999) and (with Jyoti M Rai) Empire of the Sikhs, a biography of the great Punjabi ruler Ranjit Singh (2008), put Sikh history into a much-needed modern world perspective, while the critique of US 20th-century global military interventions The World According to Washington (2004) shows its author as a polemicist at his coruscating best.

A builder's son, Patwant Singh grew up in the 1920s and 30s when Lutyens' Delhi was being created. His time at school did less for his education than the years working in his father's firm in the rough and tumble of building projects around India. In 1952, he settled in Bombay to start a magazine publishing firm. His first monthly publication was The Indian Builder, which aimed to highlight the achievements and problems of newly independent India's burgeoning building industry and its vital role in national development. The Pharmaceutist followed; its publisher knew nothing about pharmaceuticals but could see the importance of the growing industry.

He next launched Design, a revolutionary magazine critically covering architecture, urban planning, industrial design, graphics and the visual arts; areas that had hitherto had isolated and mutually uncomprehending audiences. The magazine, which Singh published and edited for 31 years, became a meeting-point for architects and artists such as Peter Blake, Walter Gropius, Philip Johnson, Richard Neutra and Eero Saarinen.

In 1962 Singh moved back to Delhi. He had perceived that the principles governing successful grafting of the new onto the old applied as much to the political sphere as to architecture and planning, and that independent India's rule-from-the-top imperial inheritance was being disastrously applied, along with wholesale acceptance of western economic and technological models, to the neglect of the traditional skills of hundreds of millions of Indians.

His crusading energies became political (his first marriage, even, was ended by political incompatibility), though he was steadfast in never aspiring to personal political power or position. His first book, India and the Future of Asia (1966), was published by Alfred A Knopf in New York and Faber & Faber in London at this time. Singh's debut as an author was as challenging as his journalism: meeting his US publisher, he immediately criticised his tie-and-shirt combination.

The first of a series of discussions he undertook with the prime minister Indira Gandhi led in 1974 to the setting up of a statutory body to monitor new building projects and conserve historic structures in Delhi. As usual, this turned out to be only as good as the individuals who ran it. Its instigator's campaign for rational urban planning and conservation, however, was unceasing, even after he suffered a massive heart attack in 1977. More than 30 years later, he was still fulminating at the wholesale destruction of Delhi's 3,000-year built heritage in blind pursuit of profit-led development, and two days after his death his article on the folly of holding the Commonwealth Games 2010 in Delhi appeared in the Financial Times.

During the 1984 crisis at the Golden Temple, the central shrine of Sikhism in Amritsar, Singh embodied the best conscience of the nation in his attempts at personal intercession to try to prevent the fatal confrontation that duly took place between the Sikh hard-liners in the Golden Temple and the Indian army. What helped to sustain him through this tragic time was writing The Golden Temple, published in 1989, his classic account of the much misunderstood Sikh faith and how this essentially peaceful religion, combining many of the precepts of Islam and Hinduism, was born and forged.

As chairman of a family trust, Singh built the Kabliji Hospital and Rural Health Centre outside Delhi, to serve villages previously without any medical resources. His devoted second wife Meher has been responsible for its administration.

At the end of his book The Sikhs, Singh memorably portrays his co-religionists, and himself: "Because they wear the outward symbols of their faith with pride, they stand out for their distinctive appearance, good humour, and just a touch of swagger." Add "and new vision with old values" to complete the personal portrait.